I. Field of the Invention
The present invention relates generally to group messaging and more particularly to a method and apparatus for efficiently controlling group multicast messaging in a wireless network.
II. Description of the Related Art
Traditional network computing applications involve communication between two computers. In such networks, data is transmitted from one computer to another computer in a point-to-point manner. That is, data from one computer is sent to the other computer, and no other.
However, some important emerging applications, such as LAN TV, desktop conferencing, corporate broadcasts, and collaborative computing, require data transmission in a xe2x80x9cpoint-to-multipointxe2x80x9d fashion, that is, transmitting data to multiple recipients simultaneously. Such applications would require a tremendous amount of network bandwidth to be effectively implemented using the point-to-point technique. For example, using a traditional point-to-point transmission scheme would require the same information to be transmitted n times, where n represents the number of recipients. The bandwidth required to accomplish such a task would grow in proportion to the number of computers receiving the transmission. Such an approach is infeasible for applications where large data transmissions, such as audio and video, need to be sent to a large number of recipients.
To effectively implement the transfer of large quantities of data in a point-to-multipoint network, a broadcast design has been proposed. In a broadcast design, data is broken into packets, each packet addressed to a xe2x80x9cbroadcast addressxe2x80x9d, rather than addressing multiple copies of each packet to each recipient desiring the information. However, if this technique is used, the network must generally send the information packets throughout the entire network so that anyone desiring reception of the information can xe2x80x9clistenxe2x80x9d to the broadcast address and receive the information. Sending information packets everywhere is a significant use of network resources if only a small group of recipients desire the information.
To overcome this problem, a technique known as IP multicast has been developed for use in wired IP networks. With IP multicast, applications can send one copy of each data packet and address it to a group of recipients that wish to receive the information generated by an application. This technique addresses data packets to a group of recipients rather than to individual recipients, and it relies on the network to forward the data packets only to paths that have a sub-network that needs the information, i.e., a sub-network having at least one recipient desiring the particular IP multicast. An example of a subnetwork is a local broadcast network, such as an Ethernet LAN.
Applications for point-to-multipoint communications in wireless networks have not yet been widely implemented, due to the large bandwidth necessary to accommodate such communications. However, increases in wireless data rates, and hence bandwidth, indicate that such applications may eventually become used in such wireless networks.
In a wireless network, users of wireless communication devices communicate over an air-interface to a central computer. This may be done directly, as in the case of a wireless LAN in an office environment, or it may be done through cellular infrastructure equipment, as in the case of a wireless telephone application. In such wireless networks, it would be desirable to limit multicast transmissions to a specific geographic area having at least one user desiring reception. Since the broadcast sub-network for a wireless network usually corresponds to a particular geographic area, the process of determining which sub-networks require transmission determines which geographic areas are covered by the multicast transmission and, hence, the name xe2x80x9ccoverage control.xe2x80x9d Presently, in order to transmit a multicast transmission in a wireless network, the transmission must be sent to all end devices, regardless of whether or not the multicast transmission is desired.
The present invention is a method and apparatus for providing coverage control for multicast service in a wireless network. The present invention allows multicast transmissions to be efficiently distributed in a wireless network by limiting transmissions of multicast information to a subset of available devices in the wireless network.
In one embodiment, the present invention is an apparatus for providing coverage control for multicast service in a wireless network, the wireless network comprising a central transceiver and a plurality of wireless communication devices. The present invention comprises the central transceiver, comprising a receiver for receiving a membership report from a wireless communication device, the membership report identifying a multicast group, the membership report provided to a processor. The processor generates an indication of the multicast group identified in the membership report and provides the indication to a transmitter for transmitting the indication to at least a portion of the plurality. of wireless communication devices.
In another embodiment, the present invention is a method for providing coverage control for multicast service in a wireless network, the wireless network comprising a central transceiver and a plurality of wireless communication devices. The present invention comprises the steps of receiving a membership report from a first wireless communication device, the membership report identifying a multicast group. An indication of the received membership report is generated by a processor contained within the central transceiver. The indication is then transmitted to at least a portion of the plurality of wireless communication devices, the indication identifying the multicast group identified in the received membership report.